1. Field of the Invention
The present invention relates to a core assembly for a pneumatic tire which permits safe running for a fixed distance in the event that the internal pressure of the pneumatic tire has declined due to a puncture or the like.
2. Description of the Related Art
Conventionally, there are numerous examples in which a core assembly formed of a light-metal material having a high rigidity and a low specific gravity is fixed to a rim. In most of these examples, however, since the core assembly is secured to the rim by means of bolts or the like, there is a drawback in that, during flat running (punctured condition), friction occurs between the tire and the core assembly owing to the difference in circumferential length between the tire and the core assembly, with the result that damage is liable to occur to the tire.
In contrast, a rotary-type core assembly is known, as disclosed in Japanese Patent Publication Issue No. 55-3163. This core assembly is formed of a resilient material, and as the rim and the core assembly come into sliding contact with each other, an improved effect is attained by remarkably preventing damage to the tire. In the case of a tire with this rotary-type core assembly fitted therein, however, there is a drawback in that, in the case where flat running of a relatively long distance is effected in a heavy-load region or a high-speed region which can exist in practical use, the surface of the core assembly contacting a well portion of the rim becomes worn owing to the friction. This can give rise to vibrations, thereby rendering the running of the vehicle practically impossible.